Question: Simplify the following expression: $4\sqrt{99}$.
First, try to factor a perfect square out of the radical. $= 4\sqrt{99}$ $= 4\sqrt{9 \cdot 11}$ Separate the radical and simplify. $= 4\sqrt{9} \cdot \sqrt{11}$ $= 4 \cdot 3 \cdot \sqrt{11}$ $= 12\sqrt{11}$